The invention relates to streamlining devices and more particularly to drag reduction structures utilized on moving vehicles.
It is well known that the drag produced by the flat or bluff front of a moving body such as a trailer would be lessened if the front surface were contoured somewhat, but until recently it has not been worth the cost or bother to manufacture semitrailers and the like having contoured fronts, or to provide contoured attachments for the front of trucks. High volumetric efficiency has been the primary design consideration for such trucks resulting in the manufacture of generally box-shaped vehicles. However, with increased fuel costs, streamlining is no longer impractical, and serious effort is being devoted toward developing an economical contoured attachment for the front ends of trailers, and perhaps the rear ends as well.
Because streamlining attachments must be fairly large, typically they are heavy as well as fairly expensive. At least one attempt has been made to develop an inflatable unit for this purpose as is exemplified in U.S. Pat. No. 2,737,411, which discloses an inflatable tail structure for a truck. This device, however, is not completely inflatable but utilizes a plate or frame member to rigidify that portion of the inflated body which is flush against the truck surface. Due to the tendency of the single inflated envelope disclosed in the above-referenced patent to assume a spherical shape, considerable stress would be experienced by the inflatable material along the edges of the mounting plate tending to tear the body loose from the vehicle. In addition, inasmuch as this structure is not compartmentalized or otherwise reinforced in a manner that would preserve its streamlined shape, it is questionable that the shape would be maintained under actual conditions of use.
There is a need, therefore, for a completely inflatable drag reducing structure which is form retaining under inflated conditions in use and which can be attached to the front of a trailer of the like in a way that no prying or destructive forces are produced tending to dislodge the structure from the trailer.